U.S. patent number 10,995,693 [Application Number 16/738,146] was granted by the patent office on 2021-05-04 for engine cooling structure.
This patent grant is currently assigned to Mazda Motor Corporation. The grantee listed for this patent is Mazda Motor Corporation. Invention is credited to Yoshiaki Hayamizu, Mikimasa Kawaguchi, Tatsuya Takahata, Keita Watanabe, Shinji Watanabe.
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United States Patent |
10,995,693 |
Watanabe , et al. |
May 4, 2021 |
Engine cooling structure
Abstract
An engine cooling structure includes a cylinder block including
a block inner peripheral wall and a block outer peripheral wall
that define a water jacket, and a spacer housed in the water
jacket. The block outer peripheral wall includes a coolant inlet
for introducing a coolant into the water jacket at one end in a
cylinder row direction. The spacer includes a peripheral wall
surrounding the block inner peripheral wall, and a dividing wall
and a distribution wall provided on the peripheral wall. The
dividing wall is provided along a circumferential direction of the
peripheral wall and protrudes outward from the peripheral wall
between a lower end and an upper end of the coolant inlet. The
distribution wall includes an upper distribution wall extending
upward from the dividing wall and a lower distribution wall
extending downward from the dividing wall.
Inventors: |
Watanabe; Shinji (Hiroshima,
JP), Takahata; Tatsuya (Hiroshima, JP),
Hayamizu; Yoshiaki (Higashihiroshima, JP), Watanabe;
Keita (Hiroshima, JP), Kawaguchi; Mikimasa
(Higashihiroshima, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Mazda Motor Corporation |
Hiroshima |
N/A |
JP |
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|
Assignee: |
Mazda Motor Corporation
(Hiroshima, JP)
|
Family
ID: |
1000005529328 |
Appl.
No.: |
16/738,146 |
Filed: |
January 9, 2020 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20200232412 A1 |
Jul 23, 2020 |
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Foreign Application Priority Data
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Jan 17, 2019 [JP] |
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JP2019-006066 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01P
3/14 (20130101); F01P 11/08 (20130101); F01P
3/02 (20130101); F02F 1/14 (20130101); F01P
5/10 (20130101); F01P 2003/006 (20130101); F01P
2003/021 (20130101); F01P 2003/001 (20130101) |
Current International
Class: |
F02F
1/14 (20060101); F01P 5/10 (20060101); F01P
3/02 (20060101); F01P 3/14 (20060101); F01P
11/08 (20060101); F01P 3/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102015006786 |
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Mar 2015 |
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DE |
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112014000928 |
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Nov 2015 |
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DE |
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S556433 |
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Jan 1980 |
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JP |
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H07127520 |
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May 1995 |
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JP |
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2015108345 |
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Jun 2015 |
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JP |
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2015108346 |
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Jun 2015 |
|
JP |
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2015190403 |
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Nov 2015 |
|
JP |
|
2016121578 |
|
Jul 2016 |
|
JP |
|
2018123742 |
|
Aug 2018 |
|
JP |
|
Other References
European Patent Office, Extended European Search Report Issued in
Application No. 20150495.8, dated May 20, 2020, Germany, 8 pages.
cited by applicant .
European Patent Office, Extended European Search Report Issued in
Application No. 20150494.1 dated Jun. 16, 2020, Germany, 7 pages.
cited by applicant.
|
Primary Examiner: Lathers; Kevin A
Attorney, Agent or Firm: Alleman Hall Creasman & Tuttle
LLP
Claims
The invention claimed is:
1. An engine cooling structure for cooling an engine body including
a plurality of cylinders arranged in a row by using a coolant, the
engine cooling structure comprising: a cylinder block including: a
block inner peripheral wall defining the plurality of cylinders;
and a block outer peripheral wall surrounding the block inner
peripheral wall to define a water jacket through which the coolant
circulates between the block outer peripheral wall and the block
inner peripheral wall; and a spacer housed in the water jacket,
wherein the block outer peripheral wall includes a coolant inlet
configured to introduce the coolant from a water pump into the
water jacket at one end in a cylinder row direction, the spacer
includes: a peripheral wall surrounding the block inner peripheral
wall to divide the water jacket into an inner space near the
plurality of cylinders and an outer space far from the plurality of
cylinders; a dividing wall provided along a circumferential
direction of the peripheral wall to divide the peripheral wall into
an upper peripheral wall and a lower peripheral wall below the
upper peripheral wall; and a distribution wall provided in a part
facing the coolant inlet of the peripheral wall in order to
distribute the coolant introduced from the coolant inlet into the
water jacket to a first side and a second side in the
circumferential direction of the peripheral wall, the distribution
wall protruding outward from the peripheral wall and extending in
an up-and-down direction, the dividing wall includes a part
protruding outward from the peripheral wall at a position between a
lower end and an upper end of the coolant inlet, and the
distribution wall includes: an upper distribution wall extending
upward from an upper surface of the dividing wall; and a lower
distribution wall extending downward from a lower surface of the
dividing wall, each of the upper distribution wall and the lower
distribution wall including a part protruding outward from the
peripheral wall at a position between a first end and a second end
of the coolant inlet in the cylinder row direction.
2. The engine cooling structure according to claim 1, wherein the
upper peripheral wall includes a guide element configured to guide
the coolant, when one of the plurality of cylinders excluding
cylinders at both ends of a cylinder row is a central cylinder, the
guide element guides the coolant such that the coolant circulates
between a wall part corresponding to the central cylinder in the
block inner peripheral wall and the upper peripheral wall, and the
coolant circulates between both end parts in the cylinder row
direction of the upper peripheral wall and the block outer
peripheral wall, and the lower peripheral wall divides the water
jacket such that the coolant circulates between the lower
peripheral wall and the block outer peripheral wall over an entire
circumference of the lower peripheral wall.
3. The engine cooling structure according to claim 2, wherein when
one of the plurality of cylinders at a first end of the cylinder
row is a first end cylinder and one of the plurality of cylinders
at a second end of the cylinder row is a second end cylinder, and a
direction orthogonal to the cylinder row direction is a width
direction, the guide element includes: two first through holes
facing a first wall part corresponding to the first end cylinder in
the block inner peripheral wall, the two first through holes being
formed at two locations of the upper peripheral wall facing each
other in the width direction; and two second through holes facing a
second wall part corresponding to the second end cylinder in the
block inner peripheral wall, the two second through holes being
formed at two locations of the upper peripheral wall facing each
other in the width direction, and the coolant inlet is provided at
a position shifted to a first end side in the cylinder row
direction from the two first through holes.
4. The engine cooling structure according to claim 1, wherein the
cylinder block includes a coolant exit provided at a position
facing the lower peripheral wall, the coolant exit being configured
to lead the coolant in the water jacket outside the cylinder block,
and the coolant exit is connected to a heat exchanger provided
outside the engine body.
5. The engine cooling structure according to claim 4, wherein the
coolant exit includes a first exit and a second exit provided at
positions different from each other in a circumferential direction
of the lower peripheral wall, and the first exit and the second
exit are respectively connected to different heat exchangers.
6. The engine cooling structure according to claim 5, wherein the
heat exchanger connected to the first exit includes an oil cooler
configured to cool a lubricant to be supplied to the engine body,
and the heat exchanger connected to the second exit includes an EGR
cooler configured to cool an EGR gas that is an exhaust gas
recirculated to an intake air to be introduced into the engine body
out of an exhaust gas discharged from the engine body.
7. The engine cooling structure according to claim 1, wherein when
one of the plurality of cylinders at the first end of the cylinder
row is a first end cylinder, the coolant inlet faces a region that
is one region of a wall part corresponding to the first end
cylinder in the block inner peripheral wall, the region being
shifted to a first end side from a central part of the cylinder row
direction of the wall part, and out of a plurality of regions
obtained by dividing a region facing the coolant inlet in the
peripheral wall by the dividing wall and the distribution wall,
when a region positioned below the dividing wall and on the first
end side in the cylinder row direction from the lower distribution
wall is a first region and a region positioned below the dividing
wall and on a second end side in the cylinder row direction from
the lower distribution wall is a second region, the lower
distribution wall is disposed at a position such that an area of
the first region is smaller than an area of the second region.
8. The engine cooling structure according to claim 1, wherein the
dividing wall and the distribution wall are formed to divide an
opening area of the coolant inlet into a first inflow part, a
second inflow part, a third inflow part, and a fourth inflow part
when viewed from an outside of the block outer peripheral wall, the
first inflow part being positioned above the dividing wall and on a
first end side in the cylinder row direction from the upper
distribution wall, the second inflow part being positioned above
the dividing wall and on a second end side in the cylinder row
direction from the upper distribution wall, the third inflow part
being positioned below the dividing wall and on the first end side
in the cylinder row direction from the lower distribution wall, the
fourth inflow part being positioned below the dividing wall and on
the second end side in the cylinder row direction from the lower
distribution wall, the water jacket includes, between the lower
peripheral wall and the block outer peripheral wall, a first lower
passage through which the coolant introduced from the third inflow
part flows and a second lower passage through which the coolant
introduced from the fourth inflow part flows, the cylinder block
includes a first coolant exit configured to lead the coolant in the
first lower passage outside the cylinder block, and a second
coolant exit configured to lead the coolant in the second lower
passage outside the cylinder block, the first coolant exit is
connected to a first heat exchanger provided outside the engine
body, and the second coolant exit is connected to a second heat
exchanger different from the first heat exchanger.
9. The engine cooling structure according to claim 8, wherein an
area of each of the first inflow part and the second inflow part is
larger than an area of either of the third inflow part and the
fourth inflow part.
10. The engine cooling structure according to claim 9, wherein the
first heat exchanger includes an oil cooler; the second heat
exchanger includes an EGR cooler; and an area of the third inflow
part is smaller than an area of the fourth inflow part.
11. The engine cooling structure according to claim 10, wherein the
upper distribution wall extends upward from the dividing wall to an
upper end of the peripheral wall.
12. The engine cooling structure according to claim 9, wherein an
area of the first inflow part and an area of the second inflow part
are set to be approximately equal to each other.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is based on Japanese Patent application No.
2019-006066 filed in Japan Patent Office on Jan. 17, 2019, the
contents of which are hereby incorporated by reference.
TECHNICAL FIELD
The present invention relates to a structure for cooling an engine
body including a plurality of cylinders by using a coolant.
BACKGROUND ART
As an engine cooling structure, a structure that cools an engine
body by circulating a coolant through a water jacket formed to
surround a cylinder wall is known. Another structure is also known
in which a spacer surrounding a cylinder wall is housed in a water
jacket and a circulation channel for a coolant in the water jacket
is separated by the spacer.
For example, Japanese Patent Application Laid-Open No. 2015-190403
discloses a structure in which a spacer is housed in a water jacket
and the spacer causes a coolant to circulate only in an upper
region of the water jacket. Specifically, Japanese Patent
Application Laid-Open No. 2015-190403 discloses an engine in which
the spacer is housed in the water jacket, and a coolant-introducing
part that introduces the coolant into the water jacket is formed on
a cylinder block outer peripheral wall. The spacer includes a
spacer upper part close to the cylinder block outer peripheral wall
and a spacer lower part close to a cylinder liner. In the spacer
upper part, an opening for introducing the coolant introduced from
the coolant-introducing part into the inside of the spacer is
formed.
With the structure of Japanese Patent Application Laid-Open No.
2015-190403, almost all of the coolant introduced from the
coolant-introducing part into the water jacket is introduced into a
space between the spacer upper part and the cylinder liner, and
almost all of the coolant circulates through the space. Therefore,
the upper part of the cylinder liner can be efficiently cooled.
In other words, with the structure of Japanese Patent Application
Laid-Open No. 2015-190403, although the coolant flows in the upper
region of the water jacket, the coolant hardly flows in the lower
region of the water jacket. That is, the lower region of the water
jacket is a dead space. Thus, there is a problem that the water
jacket is not effectively used.
SUMMARY OF INVENTION
The present invention has been made in view of the above
circumstances, and an object of the present invention is to provide
an engine cooling structure that can use the water jacket more
effectively.
An engine cooling structure according to the present invention for
solving the above problem is a structure for cooling an engine body
including a plurality of cylinders arranged in a row by using a
coolant, and includes: a cylinder block including: a block inner
peripheral wall defining the plurality of cylinders; and a block
outer peripheral wall surrounding the block inner peripheral wall
to define a water jacket through which the coolant circulates
between the block outer peripheral wall and the block inner
peripheral wall; and a spacer housed in the water jacket. The block
outer peripheral wall includes a coolant inlet configured to
introduce the coolant from a water pump into the water jacket at
one end in a cylinder row direction. The spacer includes: a
peripheral wall surrounding the block inner peripheral wall to
divide the water jacket into an inner space near the plurality of
cylinders and an outer space far from the plurality of cylinders; a
dividing wall provided along a circumferential direction of the
peripheral wall to divide the peripheral wall into an upper
peripheral wall and a lower peripheral wall below the upper
peripheral wall; and a distribution wall provided in a part facing
the coolant inlet in the peripheral wall in order to distribute the
coolant introduced from the coolant inlet into the water jacket to
a first side and a second side of the circumferential direction of
the peripheral wall, the distribution wall protruding outward from
the peripheral wall and extending in an up-and-down direction. The
dividing wall includes a part protruding outward from the
peripheral wall at a position between a lower end and an upper end
of the coolant inlet. The distribution wall includes: an upper
distribution wall extending upward from an upper surface of the
dividing wall; and a lower distribution wall extending downward
from a lower surface of the dividing wall.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic diagram showing an overall configuration of
an engine system according to an embodiment of the present
invention;
FIG. 2 is a perspective view of an engine body and peripheral
devices thereof when viewed from an exhaust side;
FIG. 3 is a perspective view of the engine body and peripheral
devices thereof when viewed from an intake side;
FIG. 4 is a perspective view showing a cylinder block and a
spacer;
FIG. 5 is a top view of the cylinder block;
FIG. 6 is a top view of the cylinder block in which the spacer is
housed;
FIG. 7 is a cross-sectional view along the line VII-VII of FIG.
6;
FIG. 8 is a cross-sectional view along the line VIII-VIII of FIG.
6;
FIG. 9 is a perspective view of the spacer;
FIG. 10 is a side view of an exhaust side of the spacer;
FIG. 11 is a side view of an intake side of the spacer;
FIG. 12 is a cross-sectional view of the spacer along the line
XII-XII of FIG. 10;
FIG. 13 is a cross-sectional view of the spacer along the line
XIII-XIII of FIG. 12;
FIG. 14 is a cross-sectional view of the spacer along the line
XIV-XIV of FIG. 7;
FIG. 15 is a cross-sectional view of the spacer along the line
XV-XV of FIG. 7;
FIG. 16 is a side view in which a vicinity of a coolant-introducing
part of the cylinder block is enlarged;
FIG. 17 is a cross-sectional view of the spacer along the line
XVII-XVII of FIG. 10;
FIG. 18 is a diagram schematically showing a flow of a coolant in
an upper region of a water jacket; and
FIG. 19 is a diagram schematically showing the flow of the coolant
in a lower region of the water jacket.
DESCRIPTION OF EMBODIMENT
An engine cooling structure according to an embodiment of the
present invention will be described below with reference to the
drawings.
(1) Overall Configuration
FIG. 1 is a schematic diagram showing a preferred embodiment of an
engine system to which the cooling structure of the present
invention is applied. An engine system 100 includes an engine body
1, a water pump 60, a radiator (RAD) 61, an automatic transmission
fluid warmer (ATF/W) 62, an oil cooler (O/C) 63, an exhaust gas
recirculation cooler (EGR/C) 64, and a heater 65. In the present
embodiment, the ATF warmer 62, the oil cooler 63, the EGR cooler
64, and the heater 65 correspond to the "heat exchanger" of the
claims.
As shown in FIG. 1, the engine body 1 is a series four-cylinder
type four-cycle engine including four substantially cylindrical
cylinders 2a to 2d arranged in a predetermined direction. The
engine body 1 is mounted on a vehicle as a drive source for
rotationally driving wheels. The engine body 1 includes a cylinder
block 3 in which the cylinders 2a to 2d are formed, and a cylinder
head 4 fastened to the cylinder block 3 covering a top surface of
the cylinder block 3. In each of the cylinders 2a to 2d, a piston
(not shown) is fitted to allow up-and-down reciprocating motion. In
each of the cylinders 2a to 2d, a crown surface of the piston and a
bottom surface of the cylinder head 4 define a combustion chamber
in which an air-fuel mixture burns. In the engine according to the
present embodiment, auto-ignition combustion in which the air-fuel
mixture is self-ignited is performed in at least a part of an
operation region. Note that FIG. 1 shows the cylinder block 3 and
the cylinder head 4 separate from each other.
Hereinafter, the four cylinders 2a to 2d formed in the cylinder
block 3 are referred to as a first cylinder 2a, a second cylinder
2b, a third cylinder 2c, and a fourth cylinder 2d, respectively, in
order from the right side of FIG. 1. Meanwhile, the first to fourth
cylinders 2a to 2d, when referred to without particular
distinction, are simply referred to as cylinders 2. As appropriate,
a direction in which the cylinders 2 are arranged, that is, a
cylinder row direction is referred to as a front-to-back direction,
a direction from the fourth cylinder 2d to the first cylinder 2a is
referred to as forward, and a direction from the first cylinder 2a
to the fourth cylinder 2d is referred to as backward. Note that
FIG. 1 shows that the cylinder head 4 is opposite to the cylinder
block 3 in a front-to-back direction, and in the cylinder head 4,
the fourth cylinder 2d is on the right side and the first cylinder
2a is on the left side. In the present embodiment, the first
cylinder 2a and the fourth cylinder 2d correspond to the "cylinders
at both ends" of the claims, and each of the second cylinder 2b and
the third cylinder 2c corresponds to the "central cylinder" of the
claims. The first cylinder 2a corresponds to the "first end
cylinder" of the claims, and the fourth cylinder 2d corresponds to
the "second end cylinder" of the claims.
In the cylinder head 4, an intake port (not shown) for introducing
intake air into the cylinder 2 and an exhaust port (not shown) for
discharging exhaust gas from the cylinder 2 are formed separately
on a first side and a second side in a width direction of the
engine body 1 orthogonal to the cylinder row direction across a
central axis of the cylinder 2. Hereinafter, as appropriate, the
width direction of the engine body 1 is referred to as a
right-to-left direction, the side on which the intake port is
formed is referred to as an intake side or left, and the opposite
side is referred to as an exhaust side or right. In FIG. 1 and
other figures, "EX" indicates the exhaust side, and "IN" indicates
the intake side.
The water pump 60 is a device that discharges a coolant for cooling
the engine body 1. A water jacket 20 through which the coolant can
circulate is formed in the cylinder block 3. The water pump 60
introduces the coolant into the water jacket 20.
Specifically, the cylinder block 3 includes a block inner
peripheral wall 2E that defines the four cylinders 2, and a block
outer peripheral wall 10 surrounding the block inner peripheral
wall 2E. The water jacket 20 is defined and formed between the
block inner peripheral wall 2E and the block outer peripheral wall
10. A coolant-introducing hole 15 is formed in the block outer
peripheral wall 10. The coolant-introducing hole 15 opens on an
outer peripheral surface of the block outer peripheral wall 10 and
communicates with the water jacket 20. The water pump 60 is fixed
to the cylinder block 3 in communication with the
coolant-introducing hole 15. The coolant discharged from the water
pump 60 is introduced into the water jacket 20 via the
coolant-introducing hole 15. In the present embodiment, the
coolant-introducing hole 15 corresponds to the "coolant inlet" of
the claims.
In the block outer peripheral wall 10, a first block side outlet
hole 16 and a second block side outlet hole 17 are formed in
addition to the coolant-introducing hole 15. Each of the outlet
holes 16 and 17 opens on the outer peripheral surface of the block
outer peripheral wall 10 and communicates with the water jacket 20.
In the present embodiment, the first block side outlet hole 16 and
the second block side outlet hole 17 correspond to the "coolant
exit" of the claims. The first block side outlet hole 16
corresponds to the "first exit" of the claims, and the second block
side outlet hole 17 corresponds to the "second exit" of the
claims.
The radiator 61 is a device for cooling the coolant, and cools the
coolant circulating inside by a running wind, a cooling fan, or the
like of a vehicle.
The ATF warmer 62 is a device for warming automatic transmission
fluid (ATF), which is a working oil for an automatic transmission 9
(see FIG. 2). That is, in the present embodiment, the automatic
transmission 9 that transmits rotation of the engine body 1 to an
axle while shifting the rotation is connected to the engine body 1.
The ATF warmer 62 warms the ATF in the automatic transmission 9. In
the ATF warmer 62, passages through which the ATF and the coolant
circulate are formed. The ATF is heated by heat exchange between
the ATF and the coolant circulating through the passages in the ATF
warmer 62.
The oil cooler 63 is a device for cooling an engine oil, which is a
lubricant for lubricating each part of the engine body 1. In the
oil cooler 63, passages through which the engine oil and the
coolant circulate are formed. The engine oil is cooled by heat
exchange between the engine oil and the coolant circulating through
the passages in the oil cooler 63.
The EGR cooler 64 is a device for cooling an EGR gas. That is, in
the present embodiment, an EGR passage (not shown) that causes an
exhaust passage (not shown) and an intake passage (not shown)
connected to the engine body 1 to communicate with each other is
provided in order to introduce a part of the exhaust gas discharged
from the engine body 1 into the engine body 1. The EGR cooler 64 is
provided in the EGR passage. The EGR cooler 64 cools the EGR gas,
which is an exhaust gas recirculated to intake air (intake air to
be introduced into the engine body 1) through the EGR passage. In
the EGR cooler 64, passages through which the EGR gas and the
coolant circulate are formed. The EGR gas is cooled by heat
exchange between the EGR gas and the coolant circulating through
the passages in the EGR cooler 64.
The heater 65 is a heater for heating (air conditioning) for
introducing warm air into a vehicle interior or the like. In the
heater 65, passages through which air and the coolant circulate are
formed. The air is heated by heat exchange between the air and the
coolant circulating through the passages in the heater 65.
In this way, the coolant cools the engine body 1 and performs heat
exchange with an object fluid in each device. The engine system 100
is provided with a plurality of passages for circulating the
coolant between the water pump 60, and the engine body 1 and each
device. Specifically, the engine system 100 includes: a main
passage L10 that circulates the coolant between the water pump 60
and the radiator 61; a first auxiliary passage L20 that circulates
the coolant between the water pump 60, and the ATF warmer 62 and
the oil cooler 63; and a second auxiliary passage L30 that
circulates the coolant between the water pump 60, and the EGR
cooler 64 and the heater 65.
The main passage L10 includes the coolant-introducing hole 15, the
water jacket 20, a first head side jacket 4a, a radiator
introduction passage L11, and a radiator outlet passage L12. The
first head side jacket 4a is a passage (water jacket) formed in the
cylinder head 4 and extending in a front-to-back direction. The
radiator introduction passage L11 is a passage connecting the first
head side jacket 4a and the radiator 61. The radiator outlet
passage L12 is a passage connecting the radiator 61 and the water
pump 60.
The first head side jacket 4a is formed to pass near the center of
each cylinder 2. A rear end of the first head side jacket 4a and a
rear end of the water jacket 20 communicate with each other in an
up-and-down direction. The first head side jacket 4a opens on an
intake side surface of a front end of the cylinder head 4, and the
radiator introduction passage L11 is connected to an opening 4c
(hereinafter referred to as a first head side outlet part 4c).
In the main passage L10, the coolant discharged from the water pump
60 flows into the water jacket 20 through the coolant-introducing
hole 15, enters the first head side jacket 4a from a rear end of
the water jacket 20, and then flows into the radiator introduction
passage L11 through the first head side outlet part 4c. Thereafter,
the coolant is cooled by the radiator 61 and returns to the water
pump 60 again through the radiator outlet passage L12.
In the radiator outlet passage L12, a main switching device TS1
that opens and closes the radiator outlet passage L12 and thus the
main passage L10 is provided. The main switching device TS1
includes a thermostat and a switching valve. When the temperature
of the coolant circulating through the radiator outlet passage L12
is lower than a predetermined temperature, the switching valve of
the main switching device TS1 is closed, and circulation of the
coolant through the main passage L10 stops. On the other hand, when
the temperature of the coolant circulating through the radiator
outlet passage L12 is equal to or higher than the predetermined
temperature, the switching valve of the main switching device TS1
is opened, and the coolant can circulate through the main passage
L10. This predetermined temperature is set at about 95.degree. C.,
for example. In the present embodiment, the predetermined
temperature is changed based on a command from a power control
module (PCM) provided in a vehicle. Note that the PCM is a device
for controlling each part of the engine system 100, and as is well
known, the PCM is a microprocessor including a central processing
unit (CPU), a read-only memory (ROM), a random access memory (RAM),
and the like.
The first auxiliary passage L20 includes the coolant-introducing
hole 15, the water jacket 20, the first block side outlet hole 16,
an ATF warmer introduction passage L21, an ATF warmer outlet
passage L22, and an oil cooler outlet passage L23. The ATF warmer
introduction passage L21 is a passage connecting the first block
side outlet hole 16 and the ATF warmer 62. The ATF warmer outlet
passage L22 is a passage connecting the ATF warmer 62 and the oil
cooler 63. The oil cooler outlet passage L23 is a passage
connecting the oil cooler 63 and the water pump 60.
In the first auxiliary passage L20, the coolant discharged from the
water pump 60 flows into the water jacket 20 through the
coolant-introducing hole 15, and is then led out from the first
block side outlet hole 16 to the ATF warmer introduction passage
L21. Then, the coolant flows into the ATF warmer 62 to heat the
ATF, and then flows into the oil cooler 63 through the ATF warmer
outlet passage L22. The coolant cooled down by heating the ATF
cools the oil in the oil cooler 63, and then returns to the water
pump 60 through the oil cooler outlet passage L23.
In the ATF warmer introduction passage L21, a first auxiliary
switching device TS2 that opens and closes the ATF warmer
introduction passage L21 and thus the first auxiliary passage L20
is provided. The first auxiliary switching device TS2 includes a
thermostat and a switching valve. When the temperature of the
coolant circulating through the ATF warmer introduction passage L21
is lower than a predetermined temperature, the switching valve of
the first auxiliary switching device TS2 is closed, and circulation
of the coolant through the first auxiliary passage L20 stops. On
the other hand, when the temperature of the coolant circulating
through the ATF warmer introduction passage L21 is equal to or
higher than the predetermined temperature, the switching valve of
the first auxiliary switching device TS2 is opened, and the coolant
can circulate through the first auxiliary passage L20. This
predetermined temperature is set at about 65.degree. C., for
example.
The second auxiliary passage L30 includes the coolant-introducing
hole 15, the water jacket 20, the second block side outlet hole 17,
an EGR cooler introduction passage L31, an EGR cooler outlet
passage L32, a heater outlet passage L33, a second head side jacket
4b, and a head outlet passage L34. The EGR cooler introduction
passage L31 is a passage connecting the second block side outlet
hole 17 and the EGR cooler 64. The EGR cooler outlet passage L32 is
a passage connecting the EGR cooler 64 and the heater 65. The
heater outlet passage L33 is a passage connecting the heater 65 and
the second head side jacket 4b. The second head side jacket 4b is a
passage (water jacket) formed in the cylinder head 4 and extending
in a front-to-back direction. The head outlet passage L34 is a
passage connecting the second head side jacket 4b and the water
pump 60.
The second head side jacket 4b is positioned on the exhaust side of
the first head side jacket 4a, and passes around the exhaust port
of each cylinder 2. The second head side jacket 4b is open at the
rear end of the exhaust side surface of the cylinder head 4, and
the heater outlet passage L33 is connected to an opening 4d
(hereinafter referred to as a head side introduction part 4d). The
second head side jacket 4b is open at the front end of the exhaust
side surface of the cylinder head 4, and an opening 4e (hereinafter
referred to as a second head side outlet part 4e) and the head
outlet passage L34 are connected.
In the cylinder head 4, a communication passage 4f connecting the
first head side jacket 4a and the second head side jacket 4b is
provided. A part of the coolant in the first head side jacket 4a
can flow into the second head side jacket 4b through the
communication passage 4f.
In the second auxiliary passage L30, the coolant discharged from
the water pump 60 flows into the water jacket 20 through the
coolant-introducing hole 15, and is then led out from the second
block side outlet hole 17 to the EGR cooler introduction passage
L31. Then, the coolant flows into the EGR cooler 64 to cool the EGR
gas, and then flows into the heater 65 through the EGR cooler
outlet passage L32. The coolant warmed up by cooling the EGR gas
heats the air in the heater 65, and then passes through the heater
outlet passage L33 and enters the second head side jacket 4b via
the head side introduction part 4d. The coolant cooled down by
heating the air in the heater 65 moves forward in the second head
side jacket 4b while cooling the cylinder head 4, and returns to
the water pump 60 through the second head side outlet part 4e and
the head outlet passage L34.
In the head outlet passage L34, a second auxiliary switching device
SV1 that opens and closes the head outlet passage L34 and thus the
second auxiliary passage L30 is provided. The second auxiliary
switching device SV1 includes a solenoid valve that opens and
closes the head outlet passage L34. An opening degree of the
solenoid valve can be changed to a fully closed position, a fully
opened position, or an intermediate opening degree between the
fully closed position and the fully opened position, and is changed
by the PCM according to an engine operating state or the like. When
the solenoid valve is closed, circulation of the coolant in the
second auxiliary passage L30 stops. When the solenoid valve is
opened, the coolant can circulate through the second auxiliary
passage L30.
Here, each of the passages L10, L20, and L30 includes the water
jacket 20. However, as will be described later, the water jacket 20
is divided by a spacer 30 into a passage constituting a part of the
main passage L10, a passage constituting a part of the first
auxiliary passage L20, and a passage constituting a part of the
second auxiliary passage L30.
(2) Structure Around the Engine
FIG. 2 is a perspective view of the engine body 1 and peripheral
devices thereof when viewed from the exhaust side. FIG. 3 is a
perspective view of the engine body 1 and peripheral devices
thereof when viewed from the intake side. FIG. 4 is a perspective
view showing the cylinder block 3 and the spacer 30. FIG. 5 is a
top view of the cylinder block 3 with the spacer 30 not housed in
the water jacket 20.
The engine body 1 includes, in addition to the cylinder block 3 and
the cylinder head 4, a head cover 6 covering a camshaft or the like
provided above the cylinder head 4, various auxiliary machines 7,
and an oil pan 5 provided below the cylinder block 3. The automatic
transmission 9 is disposed backward of the cylinder block 3. The
radiator 61 is disposed on the intake side of the engine body
1.
As shown in FIG. 5 and other figures, the block outer peripheral
wall 10 is formed in a substantially rectangular shape. The block
outer peripheral wall 10 includes an exhaust side wall 11 extending
in a front-to-back direction on the exhaust side, an intake side
wall 12 extending substantially parallel to the exhaust side wall
11 on the intake side, a front side wall 13 extending in a
right-to-left direction between the front end of the exhaust side
wall 11 and the front end of the intake side wall 12, and a rear
side wall 14 extending in a right-to-left direction between the
rear end of the exhaust side wall 11 and the rear end of the intake
side wall 12.
In the block outer peripheral wall 10, a plurality of bolt holes 19
opened on an upper surface thereof is formed. Head bolts for
fastening the cylinder block 3 and the cylinder head 4 are screwed
into the bolt holes 19. Each of the exhaust side wall 11 and the
intake side wall 12 is provided with bulging parts 18 each bulging
inward (toward the block inner peripheral wall 2E) at the front
end, the rear end, and intermediate positions facing boundaries
between the adjacent cylinders 2. One bolt hole 19 is formed in
each of the bulging parts 18.
As shown in FIG. 3, the water pump 60 is coupled to a crankshaft
via a belt 8a and a plurality of pulleys 8b and is driven by the
crankshaft, that is, by the engine, to discharge the coolant. The
water pump 60 is fixed to the front end of the exhaust side wall
11. The coolant-introducing hole 15 is formed at the front end of
the exhaust side wall 11. As shown in FIG. 5 and other figures, the
coolant-introducing hole 15 is positioned forward of the center of
the first cylinder 2a in a front-to-back direction. In more detail,
the coolant-introducing hole 15 faces a part of a front side and
exhaust side of a wall part (first cylinder wall 2e1 described
later) corresponding to the first cylinder 2a in the block inner
peripheral wall 2E, the part being curved such that the part is
positioned closer to the intake side as the part is closer to the
front.
As shown in FIG. 3, the first head side outlet part 4c is open at
the front end of the intake side surface of the cylinder head 4.
The radiator introduction passage L11 extends leftward from the
front end of the intake side surface of the cylinder head 4 toward
the radiator 61. The radiator outlet passage L12 passes forward of
the engine body 1 and extends from the radiator 61 to the water
pump 60. As shown in FIG. 2, the main switching device TS1 is
provided near the water pump 60.
As shown in FIGS. 3, 5 and other figures, the first block side
outlet hole 16 is formed in the intake side wall 12. The first
block side outlet hole 16 is formed at a position facing the second
cylinder 2b. The ATF warmer 62 is disposed close to the rear end of
the intake side part of the oil pan 5. The ATF warmer introduction
passage L21 extends from the first block side outlet hole 16 to the
ATF warmer 62 along the intake side surface of the engine body 1.
As shown in FIG. 2, the oil cooler 63 is fixed to a lower part of
the exhaust side surface of the cylinder block 3. The ATF warmer
outlet passage L22 passes below the oil pan 5 and extends from the
ATF warmer 62 to the oil cooler 63. The oil cooler outlet passage
L23 extends obliquely upward and forward from the oil cooler 63,
and is connected to the water pump 60 at the upper end thereof.
As shown in FIGS. 2, 5 and other figures, the second block side
outlet hole 17 is formed in the exhaust side wall 11. The second
block side outlet hole 17 is formed at a position facing the fourth
cylinder 2d. The EGR cooler 64 is disposed backward of the cylinder
block 3 to extend to the right and left. The EGR cooler
introduction passage L31 extends from the second block side outlet
hole 17 so as to go around an upper part of the EGR cooler 64 and
is connected to a lower surface of the EGR cooler 64. The EGR
cooler outlet passage L32 extends upward from the EGR cooler 64.
Although the heater 65 is not shown in FIG. 2, the EGR cooler
outlet passage L32 extends to the heater 65. The head side
introduction part 4d is open at the rear end of the exhaust side
surface of the cylinder head 4. The heater outlet passage L33
extends from the heater 65 to the rear end of the exhaust side
surface of the cylinder head 4. The second head side outlet part 4e
is open at the front end of the exhaust side surface of the
cylinder head 4. The head outlet passage L34 extends rightward from
the front end of the exhaust side surface of the cylinder head 4
and then extends downward, and is connected to the water pump 60 at
its lower end. The second auxiliary switching device SV1 is
provided in an intermediate part of an up-and-down direction of the
head outlet passage L34.
(3) Detailed Structure of the Spacer and the Water Jacket
The detailed structure of the spacer 30 and the water jacket 20
will be described.
FIG. 6 is a drawing corresponding to FIG. 5 and is a top view of
the cylinder block 3 with the spacer 30 housed in the water jacket
20. FIG. 7 is a cross-sectional view along the line VII-VII of FIG.
6. FIG. 8 is a cross-sectional view along the line VIII-VIII of
FIG. 6. FIG. 9 is a perspective view of the spacer 30. FIG. 10 is a
side view of the exhaust side of the spacer 30, and FIG. 11 is a
side view of the intake side of the spacer 30. FIG. 12 is a
cross-sectional view of the spacer 30 along the line XII-XII of
FIG. 10. FIG. 13 is a cross-sectional view of the spacer 30 along
the line XIII-XIII of FIG. 12. FIG. 14 is a cross-sectional view
along the line XIV-XIV of FIG. 7. FIG. 15 is a cross-sectional view
along the line XV-XV of FIG. 7.
The spacer 30 is housed in the water jacket 20 in contact with a
bottom surface of the water jacket 20. The spacer 30 is made of,
for example, a material (for example, a synthetic resin) having a
lower thermal conductivity than a material of the cylinder block 3
(for example, an aluminum alloy).
The spacer 30 includes a peripheral wall 31 surrounding the entire
outer periphery of the block inner peripheral wall 2E defining each
cylinder 2. The peripheral wall 31 divides the water jacket 20 into
an inner space close to the cylinders 2 and an outer space far from
the cylinders 2. The block inner peripheral wall 2E and the
peripheral wall 31 extend in a substantially arc shape in top view
along each cylinder 2.
The block inner peripheral wall 2E integrally includes a first
cylinder wall 2e1 defining the first cylinder 2a, a second cylinder
wall 2e2 defining the second cylinder 2b, a third cylinder wall 2e3
defining the third cylinder 2c, and a fourth cylinder wall 2e4
defining the fourth cylinder 2d. The first cylinder wall 2e1 to the
fourth cylinder wall 2e4 are each formed in a cylindrical shape and
connected to each other. An inter-bore part 2f is formed between
the cylinders 2 adjacent to each other, that is, between the first
cylinder wall 2e1 and the second cylinder wall 2e2, between the
second cylinder wall 2e2 and the third cylinder wall 2e3, and
between the third cylinder wall 2e3 and the fourth cylinder wall
2e4. In other words, the inter-bore part 2f is a part shared
between adjacent cylinder walls.
The peripheral wall 31 of the spacer 30 has a shape in which four
circles are slightly overlapped and connected in top view and the
overlap part is removed, corresponding to the shape of the block
inner peripheral wall 2E described above. The peripheral wall 31
has a height similar to the depth of the water jacket 20.
Accordingly, almost the entire water jacket 20 is divided into the
inner space and the outer space by the peripheral wall 31.
The peripheral wall 31 includes first guide element 38 at a
position facing the first cylinder wall 2e1. The first guide
element 38 includes a pair of through holes penetrating the
peripheral wall 31, that is, an intake side first through hole 38i
and an exhaust side first through hole 38e. Both the first through
holes 38i and 38e face each other in a right-to-left direction. In
more detail, the intake side first through hole 38i faces an intake
side surface at the rear of the first cylinder wall 2e1, and the
exhaust side first through hole 38e faces an exhaust side surface
at the rear of the first cylinder wall 2e1. Both the first through
holes 38i and 38e are formed to face a range from a position
slightly backward of the center in a front-to-back direction of the
first cylinder wall 2e1 to a position slightly forward of the rear
end of the first cylinder wall 2e1 (boundary between the first
cylinder wall 2e1 and the second cylinder wall 2e2).
The peripheral wall 31 includes second guide element 39 at a
position facing the fourth cylinder wall 2e4. The second guide
element 39 includes a pair of through holes penetrating the
peripheral wall 31, that is, an intake side second through hole 39i
and an exhaust side second through hole 39e. Both the second
through holes 39i and 39e face each other in a right-to-left
direction. In more detail, the intake side second through hole 39i
faces the intake side surface at the central part in a
front-to-back direction of the fourth cylinder wall 2e4, and the
exhaust side second through hole 39e faces the exhaust side surface
at the central part in a front-to-back direction of the fourth
cylinder wall 2e4. Both the second through holes 39i and 39e are
formed to face a range including the center in a front-to-back
direction of the fourth cylinder wall 2e4 and excluding the front
end and the rear end of the fourth cylinder wall 2e4.
The outer space of the peripheral wall 31 and the inner space of
the peripheral wall 31 communicate with each other via the first
guide element 38 (intake side and exhaust side first through holes
38i and 38e) and the second guide element 39 (intake side and
exhaust side second through holes 39i and 39e) described above. In
the present embodiment, the first guide element 38 and the second
guide element 39 correspond to the "guide element" of the claims,
the intake side and exhaust side first through holes 38i and 38e
correspond to the "first through hole" of the claims, and the
intake side and exhaust side second through holes 39i and 39e
correspond to the "second through hole" of the claims.
(Dividing Wall)
The spacer 30 includes a dividing wall 35 dividing the peripheral
wall 31 vertically. The dividing wall 35 is provided over the
entire circumference of the peripheral wall 31 and divides the
peripheral wall 31 into an upper peripheral wall 32 and a lower
peripheral wall 33. In other words, the spacer 30 includes the
upper peripheral wall 32, the lower peripheral wall 33 below the
upper peripheral wall 32, and the dividing wall 35 formed at a
boundary between the upper peripheral wall 32 and the lower
peripheral wall 33.
The dividing wall 35 includes an intermediate flange 35a and a step
35b.
Specifically, the peripheral wall 31 is provided with the
intermediate flange 35a protruding outward (toward the block outer
peripheral wall 10) from an intermediate position in an up-and-down
direction of the outer peripheral surface thereof. The intermediate
flange 35a is formed over the entire circumference of the
peripheral wall 31. As shown in FIGS. 7 and 8, the intermediate
flange 35a protrudes to a vicinity of the block outer peripheral
wall 10. With this configuration, the space between the peripheral
wall 31 and the block outer peripheral wall 10, that is, the space
outside the peripheral wall 31 in the water jacket 20 is divided
into spaces above and below the intermediate flange 35a over the
entire circumference of the peripheral wall 31.
Furthermore, a part of the peripheral wall 31 from the rear end of
the first guide element 38 to the front end of the second guide
element 39 is formed such that the lower peripheral wall 33 is
positioned inside the upper peripheral wall 32 (near the block
inner peripheral wall 2E) on both the intake side and the exhaust
side. The step 35b is formed to extend inward from the lower end of
the upper peripheral wall 32 toward the upper end of the lower
peripheral wall 33 so as to connect the upper peripheral wall 32
and the lower peripheral wall 33.
The intermediate flange 35a and the step 35b are provided at the
same height position. In the part of the peripheral wall 31 from
the rear end of the first guide element 38 to the front end of the
second guide element 39, the peripheral wall 31 is divided into the
upper peripheral wall 32 and the lower peripheral wall 33 by the
intermediate flange 35a and the step 35b. Hereinafter, as
appropriate, the part of the peripheral wall 31 from the rear end
of the intake side first through hole 38i to the front end of the
intake side second through hole 39i, and the part from the rear end
of the exhaust side first through hole 38e to the front end of the
exhaust side second through hole 39e are collectively referred to
as a central peripheral wall 130.
As shown in FIG. 7 and other figures, the step 35b protrudes to a
vicinity of the block inner peripheral wall 2E. With this
configuration, the space between the central peripheral wall 130
and the block inner peripheral wall 2E, that is, the space inside
the central peripheral wall 130 in the water jacket 20 is divided
into spaces above and below the step 35b substantially over the
entire circumference of the central peripheral wall 130.
The intermediate flange 35a and the step 35b are connected to each
other in each of the guide elements 38 and 39, and constitute lower
surfaces of the through holes (38i, 38e, 39i, 39e) constituting the
guide elements 38 and 39. That is, each of the guide elements 38
and 39 is formed in the upper peripheral wall 32 constituting a
part of the peripheral wall 31 above the intermediate flange 35a
and the step 35b, and is formed as a through hole with the
intermediate flange 35a and the step 35b as lower surfaces.
The step 35b is not formed in a part of the peripheral wall 31
forward of the front end of the first guide element 38, that is, a
part including the front end of the peripheral wall 31 and ranging
from the front end of the intake side first through hole 38i to the
front end of the exhaust side first through hole 38e (hereinafter,
as appropriate, this part is referred to as a front peripheral wall
140). In other words, the front peripheral wall 140 is divided into
the upper peripheral wall 32 and the lower peripheral wall 33 only
by the intermediate flange 35a. That is, an inner peripheral
surface of the front peripheral wall 140 is not divided vertically,
and only an outer peripheral surface is vertically divided by the
intermediate flange 35a. With this configuration, as shown in FIG.
8, at the front part of the water jacket 20 into which the front
peripheral wall 140 is inserted, only the space outside the
peripheral wall 31 (space between the peripheral wall 31 and the
block outer peripheral wall 10) is vertically divided by the
intermediate flange 35a, and the space inside the peripheral wall
31 (space between the block inner peripheral wall 2E and the
peripheral wall 31) is not divided vertically.
Similarly, the step 35b is not formed in a part of the peripheral
wall 31 on a back side of the rear end of the second guide element
39, that is, a part including the rear end of the peripheral wall
31 and ranging from the rear end of the intake side second through
hole 39i to the rear end of the exhaust side second through hole
39e (hereinafter, as appropriate, this part is referred to as a
rear peripheral wall 150). In other words, the rear peripheral wall
150 is divided into the upper peripheral wall 32 and the lower
peripheral wall 33 only by the intermediate flange 35a. That is, an
inner peripheral surface of the rear peripheral wall 150 is not
divided vertically, and only an outer peripheral surface is
vertically divided by the intermediate flange 35a. With this
configuration, at the rear part of the water jacket 20 into which
the rear peripheral wall 150 is inserted, only the space outside
the peripheral wall 31 (space between the peripheral wall 31 and
the block outer peripheral wall 10) is vertically divided by the
intermediate flange 35a, and the space inside the peripheral wall
31 (space between the block inner peripheral wall 2E and the
peripheral wall 31) is not divided vertically.
Here, as shown in FIG. 15, the lower peripheral wall 33 is close to
the block inner peripheral wall 2E over the entire circumference.
Specifically, a clearance dimension between the lower peripheral
wall 33 and the block outer peripheral wall 10 is larger than a
clearance dimension between the lower peripheral wall 33 and the
block inner peripheral wall 2E over the entire circumference of the
peripheral wall 31. That is, in the lower region of the water
jacket 20, a flow channel area is larger on the outside than on the
inside of the peripheral wall 31 (lower peripheral wall 33).
Meanwhile, as shown in FIG. 14, the upper peripheral wall 32 of the
central peripheral wall 130 is close to the block outer peripheral
wall 10, and the upper peripheral wall 32 of each of the front
peripheral wall 140 and the rear peripheral wall 150 is close to
the block inner peripheral wall 2E. That is, a clearance dimension
between the upper peripheral wall 32 of the front peripheral wall
140 and the block outer peripheral wall 10 is larger than a
clearance dimension between the upper peripheral wall 32 of the
front peripheral wall 140 and the block inner peripheral wall 2E. A
clearance dimension between the upper peripheral wall 32 of the
rear peripheral wall 150 and the block outer peripheral wall 10 is
larger than a clearance dimension between the upper peripheral wall
32 of the rear peripheral wall 150 and the block inner peripheral
wall 2E. Meanwhile, a clearance dimension between the upper
peripheral wall 32 of the central peripheral wall 130 and the block
outer peripheral wall 10 is smaller than a clearance dimension
between the upper peripheral wall 32 of the central peripheral wall
130 and the block inner peripheral wall 2E. In other words, in the
front part and rear part of the upper region of the water jacket 20
(regions corresponding to the front peripheral wall 140 and the
rear peripheral wall 150), the flow channel area is larger on the
outside than on the inside of the peripheral wall 31 (upper
peripheral wall 32). In the central part of the upper region of the
water jacket 20 (region corresponding to the central peripheral
wall 130), the flow channel area is larger on the inside than on
the outside of the peripheral wall 31.
Here, the central peripheral wall 130 extends from the rear part of
the first cylinder 2a to the front part of the fourth cylinder 2d,
and each inter-bore part 2f of the block inner peripheral wall 2E
faces the central peripheral wall 130. With this configuration, in
a part of the upper region of the water jacket 20 adjacent to each
inter-bore part 2f, the flow channel area is larger on the inside
than on the outside of the peripheral wall 31 (upper peripheral
wall 32).
(Distribution Wall)
On the outer peripheral surface of the exhaust side of the
peripheral wall 31, a distribution wall 36 extending in an
up-and-down direction and protruding outward (toward the block
outer peripheral wall 10) is provided. As shown in FIG. 9 and other
figures, the distribution wall 36 is positioned on the front side
of the exhaust side first through hole 38e. In the present
embodiment, the distribution wall 36 is positioned on the front
side of the center of the first cylinder 2a in a front-to-back
direction. The intermediate flange 35a extends in the
circumferential direction of the peripheral wall 31 so as to divide
the distribution wall 36 vertically. The distribution wall 36
includes an upper distribution wall 36a extending upward from the
intermediate flange 35a and a lower distribution wall 36b extending
downward from the intermediate flange 35a.
FIG. 16 is an enlarged view of the front end of the exhaust side of
the cylinder block 3. As shown in FIG. 16, the distribution wall 36
and the coolant-introducing hole 15 face each other. When viewed
from the outside of the coolant-introducing hole 15, the
distribution wall 36 extends in an up-and-down direction at an
intermediate position in a front-to-back direction of the
coolant-introducing hole 15. A part of the intermediate flange 35a
facing the coolant-introducing hole 15 is positioned between a
lower end and an upper end of the coolant-introducing hole 15.
Accordingly, the region facing the coolant-introducing hole 15 in
the peripheral wall 31, in other words, a region visually
recognized from the outside through the coolant-introducing hole 15
in the space between the peripheral wall 31 and the block outer
peripheral wall 10 is divided into four inflow parts shown in FIG.
16, that is, a first inflow part A1, a second inflow part A2, a
third inflow part A3, and a fourth inflow part A4. The first inflow
part A1 is a region positioned above the intermediate flange 35a
and forward of the upper distribution wall 36a. The second inflow
part A2 is a region positioned above the intermediate flange 35a
and backward of the upper distribution wall 36a. The third inflow
part A3 is a region positioned below the intermediate flange 35a
and forward of the lower distribution wall 36b. The fourth inflow
part A4 is a region positioned below the intermediate flange 35a
and backward of the lower distribution wall 36b.
Areas of the inflow parts A1 to A4 when the peripheral wall 31 is
viewed through the coolant-introducing hole 15 are areas of four
regions defined by an inner opening edge of the coolant-introducing
hole 15 and tips of the intermediate flange 35a and the
distribution wall 36 (the tips being farthest from the peripheral
wall 31). The relationship between the areas is set as follows.
That is, the area of the first inflow part A1 and the area of the
second inflow part A2 are set to be approximately equal to each
other. The area of each of the first and second inflow parts A1 and
A2 is larger than the area of either of the third and fourth inflow
parts A3 and A4. The area of the third inflow part A3 is smaller
than the area of the fourth inflow part A4. For example, the area
of the third inflow part A3 is set approximately half of the area
of the fourth inflow part A4. As described above, in the present
embodiment, the relationship of A3<A4<A1.apprxeq.A2 is
established as the relationship of the areas of the inflow parts A1
to A4. Note that the third inflow part A3 corresponds to the "first
region" of the claims, and the fourth inflow part A4 corresponds to
the "second region" of the claims.
(Rib)
As shown in FIGS. 12, 13, and other figures, in the inner
peripheral surface of the peripheral wall 31, a plurality of ribs
protruding inward (toward the block inner peripheral wall 2E) is
provided.
In each of the cylinders 2a to 2d, a pair of ribs 51a to 51d facing
each other across the center of the cylinder 2 is provided in the
peripheral wall 31. The ribs 51a to 51d are ribs extending in an
up-and-down direction, and are positioned on a plane extending in a
right-to-left direction through the centers of the cylinders 2a to
2d. Note that FIG. 13 is a diagram showing the inner peripheral
surface of the intake side of the peripheral wall 31. Although the
inner peripheral surface of the exhaust side of the peripheral wall
31 is not shown, the inner peripheral surface of the intake side
and the inner peripheral surface of the exhaust side have
substantially the same structure. The ribs 51a to 51d on the intake
side have the same structure as the ribs 51a to 51d on the exhaust
side corresponding thereto.
The pair of first ribs 51a corresponding to the first cylinder 2a
extends from the upper end to the lower end of the front peripheral
wall 140 on the plane extending in a right-to-left direction
through the center of the first cylinder 2a.
The second ribs 51b, the third ribs 51c, and the fourth ribs 51d
respectively corresponding to the second cylinder 2b, the third
cylinder 2c, and the fourth cylinder 2d extend downward from the
upper end of the lower peripheral wall 33. The fourth ribs 51d
corresponding to the fourth cylinder 2d extend downward from the
lower edge of the second guide element 39.
Ribs 51 extending in an up-and-down direction are also provided at
the front end and the rear end of the peripheral wall 31. That is,
a fifth rib 51e is provided at the front end of the peripheral wall
31 surrounding the first cylinder 2a (front peripheral wall 140),
and a sixth rib 51f is provided at the rear end of the peripheral
wall 31 surrounding the fourth cylinder 2d (rear peripheral wall
150). As shown in FIG. 17, which is a cross-sectional view passing
through the line XVII-XVII of FIG. 10, FIG. 12, and other figures,
the fifth rib 51e and the sixth rib 51f extend from the upper end
to the lower end of the peripheral wall 31.
(Flange)
The spacer 30 includes a plurality of flanges in addition to the
intermediate flange 35a.
The spacer 30 includes a pair of second flanges 42 that constitutes
a part of an opening edge above the second guide element 39 (intake
side and exhaust side second through holes 39i and 39e) and the
upper peripheral wall 32. Each second flange 42 extends from the
front end to the rear end (more accurately, a position slightly
backward of the rear end) of the second guide element 39. As shown
in FIG. 6, the second flange 42 extends from a vicinity of the
block outer peripheral wall 10 to a vicinity of the block inner
peripheral wall 2E in top view. The second flange 42 covers almost
the entire upper part of the clearance between the block outer
peripheral wall 10 and the block inner peripheral wall 2E in a
region where the second guide element 39 are formed.
The spacer 30 includes a pair of first flanges 41 each protruding
outward (toward the block outer peripheral wall 10) from the upper
end of a part where the first guide element 38 (intake side and
exhaust side first through holes 38i and 38e) are formed in the
upper peripheral wall 32. Each first flange 41 extends over the
entire first guide element 38 in a front-to-back direction. In
other words, the first flange 41 is formed to extend in a
front-to-back direction from a position corresponding to the rear
edge of the front peripheral wall 140 to a position corresponding
to the front edge of the central peripheral wall 130.
The spacer 30 includes a third flange 43 protruding outward (toward
the block outer peripheral wall 10) from the upper end of the front
peripheral wall 140. In top view, the third flange 43 is formed to
extend forward and on the intake side from the same position as the
rear end of the coolant-introducing hole 15, and to reach the same
position as the front end of the intake side first through hole
38i.
The first flange 41 of the intake side corresponding to the intake
side first through hole 38i extends backward continuously from the
rear end of the intake side of the third flange 43. The first
flange 41 of the exhaust side corresponding to the exhaust side
first through hole 38e extends backward from a position slightly
apart backward of the rear end of the exhaust side of the third
flange 43.
In this way, in the present embodiment, the flanges are provided
protruding outward substantially over the entire circumference of
the upper end of the peripheral wall 31 surrounding the first
cylinder 2a. As shown in FIG. 6 and other figures, the flanges
(first flange 41 and third flange 43) extend as a whole to the
vicinity of the block outer peripheral wall 10. Thus, almost the
entire upper part of the space between the peripheral wall 31
(front peripheral wall 140) surrounding the front part of the first
cylinder 2a and the block outer peripheral wall 10 is covered with
the flanges.
Here, as described above, the bulging part 18 is formed at the
front end of each of the exhaust side wall 11 and the intake side
wall 12. Correspondingly, in the present embodiment, the end of the
exhaust side at the front end of the third flange 43 is curved to
be recessed inward along the bulging part (hereinafter referred to
as an exhaust side first bulging part as appropriate) 18e of the
front end of the exhaust side wall 11 in top view, and has a shape
surrounding the exhaust side first bulging part 18e. Meanwhile, the
end of the intake side at the front end of the third flange 43 is
curved to be recessed inward along the bulging part (hereinafter
referred to as an intake side first bulging part as appropriate)
18i of the front end of the intake side wall 12 in top view, and
has a shape surrounding the intake side first bulging part 18i.
In the front part of the third flange 43, that is, on an upper
surface of the part of the third flange 43 extending in a
right-to-left direction along the front side wall 13, a plurality
of regulating parts 43a protruding upward is provided. The
regulating parts 43a are arranged to extend in parallel in a
front-to-back direction and arranged at almost equal intervals in a
right-to-left direction. The regulating parts 43a extend over the
entire front-to-back direction of the upper front surface of the
third flange 43.
As shown in FIG. 9 and other figures, the spacer 30 includes a
fourth flange 44 extending in an up-and-down direction and
protruding backward from the rear end of the upper peripheral wall
32. The fourth flange 44 extends from the upper end of the upper
peripheral wall 32 to the intermediate flange 35a.
As shown in FIG. 9 and other figures, the spacer 30 includes a
fifth flange 45 and a sixth flange 46 extending in the
circumferential direction of the peripheral wall 31. The sixth
flange 46 is a flange protruding outward (toward the block outer
peripheral wall 10) from the lower end of the peripheral wall 31.
The fifth flange 45 is a flange protruding outward from a position
slightly above the lower end of the peripheral wall 31. The fifth
and sixth flanges 45 and 46 are provided over the entire
circumference of the peripheral wall 31.
As shown in FIGS. 11, 15, and other figures, the spacer 30 includes
a first regulating flange 47 protruding outward from the outer
peripheral surface of the intake side of a part of the lower
peripheral wall 33 surrounding the second cylinder 2b. The first
regulating flange 47 extends in an up-and-down direction between
the intermediate flange 35a and the fifth flange 45. The first
block side outlet hole 16 is provided at a position facing the
lower peripheral wall 33. The first regulating flange 47 is
provided backward of the first block side outlet hole 16.
As shown in FIGS. 10, 15, and other figures, the spacer 30 includes
a second regulating flange 48 protruding outward from the outer
peripheral surface of the exhaust side of a part of the lower
peripheral wall 33 surrounding the fourth cylinder 2d. The second
regulating flange 48 extends in an up-and-down direction between
the intermediate flange 35a and the fifth flange 45. The second
block side outlet hole 17 is provided at a position facing the
lower peripheral wall 33. The second regulating flange 48 is
provided backward of the second block side outlet hole 17.
Furthermore, as shown in FIGS. 9, 12, and other figures, the spacer
30 includes reinforcing ribs 52 each extending in an up-and-down
direction at a part of the upper peripheral wall 32 facing each
inter-bore part 2f and protruding outward from the outer peripheral
surface of the upper peripheral wall 32. Each reinforcing rib 52
extends from a vicinity of the upper end of the upper peripheral
wall 32 to the intermediate flange 35a.
(4) Flow of the Coolant in the Water Jacket
A flow of the coolant in the water jacket 20 will be described.
FIG. 18 is a diagram schematically showing the flow in the upper
region of the water jacket 20 (space above the dividing wall 35 in
the water jacket 20). FIG. 19 is a diagram schematically showing
the flow in the lower region of the water jacket 20 (space below
the dividing wall 35 in the water jacket 20).
The coolant discharged from the water pump 60 is introduced into
the water jacket 20 through the coolant-introducing hole 15. At
this time, the coolant flows separately into each of the first
inflow part A1 to the fourth inflow part A4. The coolant having
flowed into each of the inflow parts A1 to A4 flows as follows.
(Coolant Having Flowed into the First Inflow Part A1 and the Second
Inflow Part A2)
The coolant having flowed into the first inflow part A1 formed
above the intermediate flange 35a and forward of the distribution
wall 36 circulates through the upper region of the water jacket
20.
That is, the coolant having flowed into the first inflow part A1
first passes through a part of the passage defined between the
peripheral wall 31 above the intermediate flange 35a (upper
peripheral wall 32) and the block outer peripheral wall 10, i.e.,
through a part from the coolant-introducing hole 15 to the intake
side first through hole 38i via the front side of the front end of
the upper peripheral wall 32 (hereinafter referred to as a first
upper passage 21u as appropriate), and then moves to the intake
side first through hole 38i.
In the intake side first through hole 38i, the intermediate flange
35a and the step 35b are connected to each other. In the region
backward of the intake side first through hole 38i, the space
inside the peripheral wall 31 is vertically divided by the step
35b. The upper space of this region (space above the step 35b) is
divided by the central peripheral wall 130 such that the flow
channel area is larger in the inside than in the outside. With this
configuration, most of the coolant that has reached the intake side
first through hole 38i flows into an inner passage above the step
35b and having a larger flow channel area, that is, a passage
defined between the intake side part of the upper peripheral wall
32 of the central peripheral wall 130 and the block inner
peripheral wall 2E (hereinafter referred to as a second upper
passage 22u as appropriate). Then, the coolant moves backward in
the second upper passage 22u and moves to the intake side second
through hole 39i.
In the intake side second through hole 39i, the step 35b and the
intermediate flange 35a are connected to each other. In the region
backward of the intake side second through hole 39i, the space
outside the peripheral wall 31 is divided vertically by the
intermediate flange 35a. The upper space of this region (space
above the intermediate flange 35a) is divided by the rear
peripheral wall 150 such that the flow channel area is larger in
the outside than in the inside. With this configuration, most of
the coolant that has reached the intake side second through hole
39i flows into an outer passage above the intermediate flange 35a
and having a larger flow channel area, that is, a passage defined
between the upper peripheral wall 32 of the rear peripheral wall
150 and the block outer peripheral wall 10 (hereinafter referred to
as a third upper passage 23u as appropriate). The third upper
passage 23u communicates with the first head side jacket 4a, and
the coolant that has reached the third upper passage 23u flows into
the first head side jacket 4a.
The coolant having flowed into the second inflow part A2 formed
above the intermediate flange 35a and backward of the distribution
wall 36 circulates through the upper region of the water jacket
20.
That is, the coolant having flowed into the second inflow part A2
first passes through a part of the passage defined between the
peripheral wall 31 above the intermediate flange 35a (upper
peripheral wall 32) and the block outer peripheral wall 10, i.e.,
through a part extending backward from the second inflow part A2 to
the exhaust side first through hole 38e (hereinafter referred to as
a fourth upper passage 24u as appropriate), and then moves to the
exhaust side first through hole 38e.
In the exhaust side first through hole 38e, the intermediate flange
35a and the step 35b are connected to each other. In the region
backward of the exhaust side first through hole 38e, the space
inside the peripheral wall 31 is vertically divided by the step
35b. The upper space of this region (space above the step 35b) is
divided by the central peripheral wall 130 such that the flow
channel area is larger in the inside than in the outside. With this
configuration, in a similar manner to the intake side, most of the
coolant that has reached the exhaust side first through hole 38e
flows into an inner passage above the step 35b and having a larger
flow channel area, that is, a passage defined between the exhaust
side part of the upper peripheral wall 32 of the central peripheral
wall 130 and the block inner peripheral wall 2E (hereinafter
referred to as a fifth upper passage 25u as appropriate). Then, the
coolant moves backward in the fifth upper passage 25u and reaches
the exhaust side second through hole 39e.
In a similar manner to the intake side, most of the coolant that
has reached the exhaust side second through hole 39e flows into an
outer passage having a relatively large flow channel area, that is,
the third upper passage 23u, and then flows into the first head
side jacket 4a.
Not that the third upper passage 23u is divided into the intake
side and the exhaust side by the fourth flange 44. Therefore, the
coolant flowing from the first inflow part A1 changes its direction
at an intake side part of the fourth flange 44 in the third upper
passage 23u, and flows into the first head side jacket 4a.
Meanwhile, the coolant flowing from the second inflow part A2
changes its direction at an exhaust side part of the fourth flange
44 in the third upper passage 23u, and flows into the first head
side jacket 4a.
In this way, the coolant having flowed into the first inflow part
A1 and the second inflow part A2 passes through the passage along
the upper peripheral wall 32, that is, the passage defined above
the dividing wall 35 in the water jacket 20, and is introduced into
the first head side jacket 4a. In other words, the first to fifth
upper passages 21u to 25u and the guide elements 38 and 39 through
which the coolant having flowed into the first inflow part A1 and
the second inflow part A2 passes constitute a part of the main
passage L10. Hereinafter, as appropriate, the space defined above
the dividing wall 35 in the water jacket 20 is referred to as an
upper passage 20u.
As described above, the coolant circulating through the upper
passage 20u passes outside the peripheral wall 31 in parts along
the front peripheral wall 140 and the rear peripheral wall 150. In
a part along the central peripheral wall 130, the coolant passes
inside the peripheral wall 31. Thus, the coolant does not come in
direct contact with the upper part of each of the front part of the
first cylinder wall 2e1 and the rear part of the fourth cylinder
wall 2e4. Meanwhile, the coolant comes in direct contact with the
upper part of each inter-bore part 2f and the upper parts of the
second cylinder wall 2e2 and the third cylinder wall 2e3.
In addition, in the present embodiment, the third flange 43, the
first rib 51a, and the fifth rib 51e ensure that direct contact
between the front part of the first cylinder wall 2e1 and the
coolant is avoided.
Specifically, in the vicinity of the first and second inflow parts
A1 and A2, a part of the coolant flows upward following a collision
against the front peripheral wall 140 facing the inflow parts A1
and A2. In contrast, in the present embodiment, as described above,
the upper part of the space between the coolant-introducing hole 15
and the front peripheral wall 140 is covered with the third flange
43. Therefore, in the vicinity of the first and second inflow parts
A1 and A2, the coolant is prevented from going beyond the upper end
of the front peripheral wall 140 and flowing into the inside of the
front peripheral wall 140 (clearance between the front peripheral
wall 140 and the first cylinder wall 2e1), and direct contact of
the coolant with the front part of the first cylinder wall 2e1 is
avoided.
In the first upper passage 21u along the front peripheral wall 140,
since the flow channel area is reduced by the exhaust side first
bulging part 18e and the intake side first bulging part 18i, the
speed of the coolant having flowed vigorously from the
coolant-introducing hole 15 into the first inflow part A1 is
further increased when passing by the first bulging parts 18e and
18i. With this configuration, the flow of the coolant is turbulent
on the downstream side of the first bulging parts 18e and 18i, and
the flow direction of some of the coolant is upward. In contrast,
in the present embodiment, also on the downstream side of the first
bulging parts 18e and 18i, the upper part of the space between the
front peripheral wall 140 and the block outer peripheral wall 10 is
covered with the third flange 43. Therefore, it is avoided by the
third flange 43 that the coolant goes beyond the upper end of the
front peripheral wall 140 and flows into the inside of the front
peripheral wall 140.
There is a possibility that a part of the coolant passes through
the first guide element 38 (intake side first through hole 38i and
exhaust side first through hole 38e) and then turns forward to
enter the inside of the front peripheral wall 140. In contrast, in
the present embodiment, the inner peripheral surface of the front
peripheral wall 140 is divided in the circumferential direction by
the first rib 51a and the fifth rib 51e. In other words, a
configuration is employed in which the inner peripheral surface of
the front peripheral wall 140 is not a continuous peripheral
surface by providing the first rib 51a and the fifth rib 51e.
Therefore, it is unlikely that a coolant flow along the inner
peripheral surface of the front peripheral wall 140 is formed, and
it is avoided that a part of the coolant having reached the first
guide element 38 enters the inside of the front peripheral wall
140.
In the present embodiment, the sixth rib 51f ensures that direct
contact between the rear part of the fourth cylinder wall 2e4 and
the coolant is avoided.
Specifically, in a similar manner to the fifth rib 51e described
above, the inner peripheral surface of the rear peripheral wall 150
is divided by the sixth rib 51f. With this configuration, it is
unlikely that a coolant flow along the inner peripheral surface of
the rear peripheral wall 150 is formed, and it is avoided that a
part of the coolant having passed through the second guide element
39 enters the inside of the rear peripheral wall 150 to come into
direct contact with the fourth cylinder wall 2e4.
Furthermore, in the present embodiment, it is avoided by the second
to fourth ribs 51b to 51d provided on the lower peripheral wall 33
that the coolant circulating through the second upper passage 22u
and the fifth upper passage 25u leaks below the step 35b.
Specifically, if the inner peripheral surface of the lower
peripheral wall 33 is continuous, as shown by a broken line in FIG.
13, a downward flow is easily formed along the inner peripheral
surface from the second upper passage 22u. This means that the
coolant is likely to leak downward from the second upper passage
22u. In contrast, in the present embodiment, the lower peripheral
wall 33 below the second upper passage 22u, that is, the inner
peripheral surface of the lower peripheral wall 33 facing the
intake side surface of the second to fourth cylinder walls 2e2 to
2e4 is divided by the second to fourth ribs 51b to 51d of the
intake side. Therefore, it is avoided that the flow as described
above is formed, that is, that the coolant in the second upper
passage 22u leaks downward.
This also applies to the fifth upper passage 25u. That is, the
inner peripheral surface of the lower peripheral wall 33 below the
fifth upper passage 25u is divided by the second to fourth ribs 51b
to 51d of the exhaust side. Therefore, it is avoided that a
downward flow is formed along the inner peripheral surface, that
is, that the coolant in the fifth upper passage 25u leaks
downward.
(Coolant Having Flowed into the Third Inflow Part A3 and the Fourth
Inflow Part A4)
The coolant having flowed into the third inflow part A3 formed
below the intermediate flange 35a and forward of the distribution
wall 36 circulates through the lower region of the water jacket
20.
That is, the coolant having flowed into the third inflow part A3
passes through the passage defined between the peripheral wall 31
below the intermediate flange 35a (lower peripheral wall 33) and
the block outer peripheral wall 10, moves forward from the third
inflow part A3, and then wraps around to the intake side. The
coolant having wrapped around to the intake side passes through the
passage defined between the lower peripheral wall 33 on the intake
side and the block outer peripheral wall 10, and moves backward. As
described above, the first regulating flange 47 is provided
backward of the first block side outlet hole 16 on the intake side
surface of the lower peripheral wall 33. Therefore, the first
regulating flange 47 regulates movement of the coolant backward of
the first regulating flange 47, and the coolant is introduced into
the first block side outlet hole 16. Then, the coolant passes
through the first block side outlet hole 16 and is led out of the
water jacket 20.
In this way, the coolant having flowed into the third inflow part
A3 passes through a part of the lower region of the water jacket
20, and is led out to the first block side outlet hole 16. The
passage for the coolant, that is, a passage from the third inflow
part A3 to the first regulating flange 47 through the front side of
the front end of the lower peripheral wall 33 in the space between
the lower peripheral wall 33 and the block outer peripheral wall 10
(hereafter referred to as a first lower passage 21d as appropriate)
constitutes part of the first auxiliary passage L20.
The coolant having flowed into the fourth inflow part A4 formed
below the intermediate flange 35a and backward of the distribution
wall 36 circulates through the lower region of the water jacket
20.
That is, the coolant having flowed into the fourth inflow part A4
passes through the passage defined between the peripheral wall 31
below the intermediate flange 35a (lower peripheral wall 33) and
the block outer peripheral wall 10, and moves backward. As
described above, the second regulating flange 48 is provided at a
position backward of the second block side outlet hole 17 on the
exhaust side surface of the lower peripheral wall 33. Therefore,
the second regulating flange 48 regulates movement of the coolant
backward of the second regulating flange 48, and the coolant is
introduced into the second block side outlet hole 17. Then, the
coolant passes through the second block side outlet hole 17 and is
led out of the water jacket 20.
In this way, the coolant having flowed into the fourth inflow part
A4 passes through a part of the lower region of the water jacket
20, and is led out to the second block side outlet hole 17. The
passage for the coolant, that is, a passage from the fourth inflow
part A4 to the second regulating flange 48 through the exhaust side
of the lower peripheral wall 33 in the space between the lower
peripheral wall 33 and the block outer peripheral wall 10,
(hereafter referred to as a second lower passage 22d as
appropriate) constitutes part of the second auxiliary passage
L30.
(5) Effects and the Like
As described above, the present embodiment employs a configuration
in which the region facing the coolant-introducing hole 15 in the
peripheral wall 31 of the spacer 30, in other words, the space
between the inner opening of the coolant-introducing hole 15 and
the peripheral wall 31 is divided into the first to fourth inflow
parts A1 to A4 by the dividing wall 35 and the distribution wall
36, and the coolant discharged from the water pump 60 is introduced
separately into the inflow parts A1 to A4 to circulate through
different passages. Therefore, the block inner peripheral wall 2E
(first to fourth cylinder walls 2e1 to 2e4), the EGR gas, and the
lubricant can be appropriately cooled.
Specifically, in the present embodiment, the dividing wall 35
extending in the circumferential direction is provided in the
region facing the coolant-introducing hole 15 in the peripheral
wall 31, and the water jacket 20 is divided into the upper passage
20u and the lower passages 21d and 22d by the dividing wall 35.
This makes it possible to avoid that the coolant flows unevenly
upward or downward, and to appropriately distribute the coolant to
the upper passage 20u and the lower passages 21d and 22d.
In particular, in the present embodiment, the upper passage 20u
allows the coolant to circulate so as to come in direct contact
with the second cylinder wall 2e2, the third cylinder wall 2e3, and
the plurality of (three) inter-bore parts 2f, and not to come in
direct contact with the front part of the first cylinder wall 2e1
and the rear part of the fourth cylinder wall 2e4. The lower
passages 21d and 22d allow the coolant to circulate so as not to
come in direct contact with the first to fourth cylinder walls 2e1
to 2e4. This makes it possible to implement appropriate cooling
according to temperature conditions of the first to fourth
cylinders 2a to 2d.
That is, since there are other cylinders on both sides of the
second cylinder 2b, a wall part corresponding to the second
cylinder 2b in the block inner peripheral wall 2E, that is, the
second cylinder wall 2e2 is likely to reach a high temperature.
Similarly, since there are other cylinders on both sides of the
third cylinder 2c, a wall part corresponding to the third cylinder
2c in the block inner peripheral wall 2E, that is, the third
cylinder wall 2e3 is likely to reach a high temperature. Moreover,
the inter-bore part 2f, which receives combustion energy from the
two cylinders, is likely to reach a high temperature. In
particular, upper parts of the second cylinder wall 2e2, the third
cylinder wall 2e3, and the inter-bore part 2f, which are close to
the combustion chambers, are likely to reach a higher temperature.
In the present embodiment, such a part that is likely to reach a
high temperature can be reliably cooled by direct contact with the
coolant.
Meanwhile, the coolant does not come in direct contact with other
parts that are unlikely to reach a high temperature, specifically,
the front part of the first cylinder wall 2e1, the rear part of the
fourth cylinder wall 2e4, and lower parts of the first to fourth
cylinder walls 2e1 to 2e4, making it possible to avoid excessive
cooling of the parts that are unlikely to reach a high temperature.
In particular, in the present embodiment, auto-ignition combustion
is performed in the combustion chambers. Therefore, there is a
possibility that, if the block inner peripheral wall 2E (first to
fourth cylinder walls 2e1 to 2e4) is excessively cooled, the
temperature in the combustion chambers becomes too low and
auto-ignition combustion is not stabilized. In contrast, according
to the present embodiment that can avoid the block inner peripheral
wall 2E from being excessively cooled, the stability of
auto-ignition combustion can be increased.
Here, in order to appropriately cool the second cylinder wall 2e2,
the third cylinder wall 2e3, and the inter-bore part 2f, it is
necessary to bring a sufficient amount of coolant into contact with
both the intake side part and the exhaust side part thereof. As
described above, however, when the coolant-introducing hole 15 is
formed at one end in the cylinder row direction of the cylinder
block 3, there is a possibility that the coolant introduced from
the coolant-introducing hole 15 to the water jacket 20 flows
unevenly on the first side (the side close to the
coolant-introducing hole 15) in the circumferential direction. In
particular, in the present embodiment, the coolant-introducing hole
15 is shifted forward of the center of the first cylinder 2a in a
front-to-back direction, and the peripheral wall 31 facing the
coolant-introducing hole 15 is curved toward the front side and the
intake side (curved such that a part of the peripheral wall 31 is
positioned closer to the intake side as the part is closer to the
front). Therefore, the coolant introduced into the water jacket 20
in a direction from the coolant-introducing hole 15 toward the
intake side is likely to move forward, and a flow amount of the
coolant is likely to lean to forward, that is, to the first side in
the circumferential direction of the peripheral wall 31.
In contrast, in the present embodiment, the part where the coolant
is introduced from the coolant-introducing hole 15 into the upper
passage 20u is divided by the distribution wall 36 (upper
distribution wall 36a) extending in an up-and-down direction into
the first inflow part A1 and the second inflow part A2. This makes
it possible to avoid the coolant introduced from the
coolant-introducing hole 15 into the water jacket 20 from flowing
unevenly on the first side in the circumferential direction, to
circulate a sufficient amount of coolant to each of the intake side
and the exhaust side of the upper passage 20u, and to appropriately
cool each of the intake side and the exhaust side of the second
cylinder wall 2e2, the third cylinder wall 2e3, and the inter-bore
part 2f.
Furthermore, in the present embodiment, the part where the coolant
is introduced from the coolant-introducing hole 15 into the lower
passages 21d and 22d is also divided by the distribution wall 36
(lower distribution wall 36b) extending in an up-and-down direction
into the third inflow part A3 and the fourth inflow part A4.
Therefore, distribution of the coolant to the oil cooler 63 and the
EGR cooler 64 can be optimized. That is, by adjusting the amount of
coolant introduced from the third inflow part A3 to the first lower
passage 21d and the amount of coolant introduced from the fourth
inflow part A4 to the second lower passage 22d, an appropriate
amount of coolant can be introduced into the oil cooler 63 into
which the coolant is introduced via the first lower passage 21d and
the EGR cooler 64 into which the coolant is introduced via the
second lower passage 22d. Therefore, the lubricant and the EGR gas
can be appropriately cooled by the coolant introduced into each of
the coolers 63 and 34.
In this way, in the present embodiment, the appropriate amount of
coolant can be distributed to the upper region and the lower region
of the water jacket 20, and furthermore, the appropriate amount of
coolant can be distributed to the first side and the second side of
the circumferential direction in each region. Therefore, the upper
region and the lower region of the water jacket 20 can be used as
an effective coolant circulation channel, and generation of a dead
space in the water jacket 20 can be avoided.
In the present embodiment, by using the lower passages 21d and 22d
as passages for introducing the coolant into the oil cooler 63 and
the EGR cooler 64, respectively, the coolant having a relatively
low and stable temperature can be introduced into the coolers 63
and 64. That is, the lower passages 21d and 22d are provided at
positions relatively far from the combustion chambers. The coolant
circulating through the lower passages 21d and 22d does not come in
direct contact with the block inner peripheral wall 2E. Therefore,
the coolant circulating through the lower passages 21d and 22d is
unlikely to be affected by the combustion chambers or the block
inner peripheral wall 2E, and the temperature is maintained at a
relatively low temperature. Therefore, by introducing such a
coolant into the oil cooler 63 and the EGR cooler 64, the lubricant
and the EGR gas can be reliably cooled in the coolers 63 and 64,
and temperature fluctuation of the lubricant and the EGR gas can be
suppressed.
In the present embodiment, as described above, the area of the
third inflow part A3 is smaller than the area of the fourth inflow
part A4. This makes it possible to prevent the coolant from being
introduced unevenly to the third inflow part A3, and to more
reliably introduce the appropriate amount of coolant to the coolers
63 and 64. That is, as described above, in the present embodiment,
since the coolant flowing from the coolant-introducing hole 15 into
the water jacket 20 is likely to move forward, the amount of
coolant introduced in the third inflow part A3 on the front side is
likely to be larger than the amount introduced in the fourth inflow
part A4 on the rear side. In contrast, since the areas of the
inflow parts A3 and A4 are set as described above, it is possible
to avoid that the coolant introduced into the third inflow part A3
becomes excessively large, and that the coolant introduced into the
fourth inflow part A4 becomes excessively small.
(6) Modification
The embodiment has described a case where the heat exchanger into
which the coolant circulating through the lower passages 21d and
22d is introduced includes the ATF warmer 62, the oil cooler 63,
the EGR cooler 64, and the heater 65. However, the heat exchanger
to be connected to the lower passages 21d and 22d is not limited to
these devices.
The embodiment has described a case where auto-ignition combustion
is performed in the combustion chambers, but the combustion mode is
not limited to this case.
(7) Conclusion
The embodiment and the modification described above are summarized
as follows.
An engine cooling structure is a structure for cooling an engine
body including a plurality of cylinders arranged in a row by using
a coolant, and includes: a cylinder block including: a block inner
peripheral wall defining the plurality of cylinders; and a block
outer peripheral wall surrounding the block inner peripheral wall
to define a water jacket through which the coolant circulates
between the block outer peripheral wall and the block inner
peripheral wall; and a spacer housed in the water jacket. The block
outer peripheral wall includes a coolant inlet configured to
introduce the coolant from a water pump into the water jacket at
one end in a cylinder row direction. The spacer includes: a
peripheral wall surrounding the block inner peripheral wall to
divide the water jacket into an inner space near the plurality of
cylinders and an outer space far from the plurality of cylinders; a
dividing wall provided along a circumferential direction of the
peripheral wall to divide the peripheral wall into an upper
peripheral wall and a lower peripheral wall below the upper
peripheral wall; and a distribution wall provided in a part facing
the coolant inlet in the peripheral wall in order to distribute the
coolant introduced from the coolant inlet into the water jacket to
a first side and a second side of the circumferential direction of
the peripheral wall, the distribution wall protruding outward from
the peripheral wall and extending in an up-and-down direction. The
dividing wall includes a part protruding outward from the
peripheral wall at a position between a lower end and an upper end
of the coolant inlet. The distribution wall includes: an upper
distribution wall extending upward from an upper surface of the
dividing wall; and a lower distribution wall extending downward
from a lower surface of the dividing wall.
In the cooling structure, a part of the dividing wall facing the
coolant inlet is disposed between the lower end and the upper end
of the coolant inlet in the up-and-down direction. The dividing
wall distributes the coolant introduced from the coolant inlet into
the water jacket to flow in both an upper region and a lower region
of the dividing wall. Therefore, the substantially entire water
jacket in the up-and-down direction can be effectively used as a
passage through which the coolant circulates, and the appropriate
amount of coolant can be circulated in each of the upper region and
the lower region of the dividing wall.
Furthermore, the distribution wall including the upper distribution
wall extending upward from the dividing wall and the lower
distribution wall extending downward from the dividing wall is
formed in a part of the peripheral wall of the spacer facing the
coolant inlet. Therefore, the coolant introduced from the coolant
inlet into the water jacket can be distributed to the first side
and the second side of the circumferential direction of the
peripheral wall of the spacer by the distribution wall (upper
distribution wall and lower distribution wall). In the
circumferential direction as well, the substantially entire water
jacket can be effectively used as a passage through which the
coolant circulates.
In particular, in the cooling structure, since the coolant inlet is
provided at the end of the cylinder row direction of the block
outer peripheral wall, there is a possibility that the coolant
introduced from the coolant inlet into the water jacket flows
unevenly on the first side in the circumferential direction. The
distribution wall is effective in suppressing such unevenness of
the coolant. That is, with the cooling structure in which the
distribution wall is provided on the peripheral wall of the spacer,
while the coolant inlet is provided at the end of the cylinder row
direction, the appropriate amount of coolant can be distributed to
each of the first side and the second side of the circumferential
direction of the water jacket.
As described above, with the cooling structure, the appropriate
amount of coolant can be circulated on both sides of the
up-and-down direction and the circumferential direction of the
water jacket, and the entire water jacket can be effectively used
as a circulation channel for the coolant.
In the cooling structure, preferably, the upper peripheral wall
includes guide element configured to guide the coolant. When one of
the plurality of cylinders excluding cylinders at both ends of the
cylinder row is a central cylinder, the guide element guides the
coolant such that the coolant circulates between a wall part
corresponding to the central cylinder in the block inner peripheral
wall and the upper peripheral wall, and the coolant circulates
between both end parts in the cylinder row direction of the upper
peripheral wall and the block outer peripheral wall. The lower
peripheral wall divides the water jacket such that the coolant
circulates between the lower peripheral wall and the block outer
peripheral wall over an entire circumference of the lower
peripheral wall.
With this configuration, the coolant circulates between the upper
peripheral wall and the block outer peripheral wall around the
cylinders at both ends of the cylinder row (hereinafter also
referred to as "both-end cylinders"), and the coolant circulates
between the upper peripheral wall and the block inner peripheral
wall around the central cylinder excluding the both-end cylinders.
Therefore, it is possible to implement appropriate cooling
according to temperature conditions of the central cylinder and the
both-end cylinders.
That is, since the central cylinder is adjacent to other cylinders
on both sides, the wall part corresponding to the central cylinder
in the block inner peripheral wall (hereinafter also referred to as
"central cylinder wall") is likely to reach a high temperature. In
particular, the upper part of the central cylinder wall, which is
close to the combustion chamber, is likely to reach a higher
temperature. Meanwhile, the wall parts corresponding to the
both-end cylinders in the block inner peripheral wall (hereinafter
also referred to as "both-end cylinder walls") are likely to be
lower in temperature than the central cylinder wall. In contrast,
with the above configuration, it is possible to appropriately cool
the upper part of the central cylinder wall, which is likely to
reach a high temperature, by bringing the coolant into direct
contact with the upper part of the central cylinder wall. Also, it
is possible to appropriately keep warm around the combustion
chambers of the both-end cylinders by suppressing direct contact of
the coolant with the upper parts of the both-end cylinder walls.
Therefore, the combustion chamber of each cylinder can be set at an
appropriate temperature.
With the above configuration, since the coolant circulates between
the lower peripheral wall and the block outer peripheral wall over
the entire circumference of the lower peripheral wall, it is
possible to prevent the lower part of the block inner peripheral
wall, which is relatively far from the combustion chambers and is
unlikely to reach a high temperature, from being excessively cooled
by the coolant.
Moreover, since the peripheral wall of the spacer includes the
dividing wall, while the circulation channel for the coolant
differs between the upper region and the lower region of the water
jacket as described above, the amount of coolant supplied to each
channel can be adjusted appropriately by the dividing wall.
When one of the cylinders at a first end of the cylinder row is a
first end cylinder and one of the cylinders at a second end of the
cylinder row is a second end cylinder, and a direction orthogonal
to the cylinder row direction is a width direction, the guide
element may include: two first through holes facing a wall part
corresponding to the first end cylinder in the block inner
peripheral wall, the two first through holes being formed at two
locations of the upper peripheral wall facing each other in the
width direction; and two second through holes facing a wall part
corresponding to the second end cylinder in the block inner
peripheral wall, the two second through holes being formed at two
locations of the upper peripheral wall facing each other in the
width direction. In this case, the coolant inlet is preferably
provided at a position shifted to the first end side in the
cylinder row direction from the two first through holes.
With this configuration, with a simple configuration in which a
plurality of through holes is formed in the upper peripheral wall
and the coolant inlet is disposed to have a specified positional
relationship with the through holes, it is possible to implement
the coolant circulation form described above that relatively
increases the degree of cooling for the central cylinder (that is,
a form to circulate the coolant between the upper peripheral wall
and the block outer peripheral wall around the first end cylinder
and the second end cylinder, and to circulate the coolant between
the upper peripheral wall and the block inner peripheral wall
around the central cylinder).
Preferably, the cylinder block includes coolant exit provided at a
position facing the lower peripheral wall, the coolant exit being
configured to lead the coolant in the water jacket outside the
cylinder block. The coolant exit is connected to a heat exchanger
provided outside the engine body.
With this configuration, the space between the lower peripheral
wall and the block outer peripheral wall can be used effectively as
part of the passage for supplying the coolant to the heat
exchanger. Moreover, since the lower peripheral wall is relatively
far from the combustion chambers, the temperature fluctuation of
the combustion chambers has little effect on the coolant
circulating around the lower peripheral wall. Therefore, the
coolant having a relatively stable temperature can be supplied to
the heat exchanger.
The coolant exit may include a first exit and a second exit
provided at positions different from each other in a
circumferential direction of the lower peripheral wall. In this
case, it is preferable that the first exit and the second exit are
respectively connected to different heat exchangers.
With this configuration, out of the space between the lower
peripheral wall and the block outer peripheral wall, a part from
the distribution wall to the first exit and a part from the
distribution wall to the second exit can be used as part of the
passages for supplying the coolant to heat exchangers different
from each other. Therefore, it is possible to appropriately supply
the coolant to each heat exchanger while effectively using the
space in the water jacket.
The heat exchanger connected to the first exit may include an oil
cooler configured to cool a lubricant to be supplied to the engine
body, and the heat exchanger connected to the second exit may
include an EGR cooler configured to cool an EGR gas that is an
exhaust gas recirculated to an intake air to be introduced into the
engine body out of an exhaust gas discharged from the engine
body.
With this configuration, the space between the lower peripheral
wall and the block outer peripheral wall (lower space of the water
jacket) can be used effectively as part of the passage for
supplying the coolant to the EGR cooler and the oil cooler.
Moreover, since the space between the lower peripheral wall and the
block outer peripheral wall is away from the combustion chambers in
both the up-and-down direction and the radial direction of the
cylinder, the coolant circulating in the space is maintained at a
relatively low temperature. Therefore, by supplying the
low-temperature coolant to the EGR cooler and the oil cooler, the
coolers can reliably cool the EGR gas and the lubricant.
When one of the cylinders at the first end of the cylinder row is
the first end cylinder, the coolant inlet may face a region that is
one region of the wall part corresponding to the first end cylinder
in the block inner peripheral wall, the region being shifted to the
first end side from a central part of the cylinder row direction of
the wall part. In this case, out of a plurality of regions obtained
by dividing the region facing the coolant inlet in the peripheral
wall by the dividing wall and the distribution wall, when a region
positioned below the dividing wall and on the first end side in the
cylinder row direction from the lower distribution wall is a first
region and a region positioned below the dividing wall and on a
second end side in the cylinder row direction from the lower
distribution wall is a second region, the lower distribution wall
is preferably disposed at a position such that an area of the first
region is smaller than an area of the second region.
With this configuration, when the coolant inlet is provided to face
the wall part corresponding to the first end cylinder in the block
inner peripheral wall (hereinafter referred to as "first end
cylinder wall"), unevenness of the coolant resulting from the
position of the coolant inlet can be suppressed.
That is, with the above configuration, since the region of the
first end cylinder wall shifted to the first end side from the
central part thereof in the cylinder row direction faces the
coolant inlet, the coolant introduced from the coolant inlet into
the water jacket is likely to flow toward the first end side in the
cylinder row direction. Meanwhile, with the above configuration,
out of the region facing the coolant inlet in the peripheral wall
of the spacer, the area of the first region that introduces the
coolant downward and to the first end side in the cylinder row
direction is smaller than the area of the second region that
introduces the coolant downward and to the second end side in the
cylinder row direction. Therefore, in the space between the lower
peripheral wall and the block outer peripheral wall, it is possible
to suppress the coolant introduced from the coolant inlet from
being uneven on the first end side in the cylinder row
direction.
Although the present invention has been fully described by way of
example with reference to the accompanying drawings, it is to be
understood that various changes and modifications will be apparent
to those skilled in the art. Therefore, unless otherwise such
changes and modifications depart from the scope of the present
invention hereinafter defined, they should be construed as being
included therein.
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